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What is the best way to repair a small leak in a non-pressurized PVC drain pipe?

I have a slow (approximately 10 mL per 10 minute) leak in a PVC drain pipe. Cutting out and repairing the entire section would be extremely annoying, and I'd undoubtedly introduce another leak. Has anyone had success repairing a non-pressurized leak in PVC with caulk, or a specialty product such as http://plast-aid.com/ ? Specifically, could I just fill up the space between the reducing bushing and the coupling shown in the picture?

You could buy a cheap plastic welder from harbor freight. Unfortunately on their website I could not find the $20 model. Epoxies can have problems because their seal can loosen from thermal cycling because of different expansion rates than PVC. If you don't want to buy a plastic welding kit you could use a smaller sliver of PVC from a spare piece of pipe, a hot air gun or soldering iron to melt the sliver of PVC and bond it with the PVC pipe.

But, until then I would mash a healthy wad of JB Weld water putty on there. I'm not sure of normal epoxy putty sets under/ in the presence of water (it might, never looked into it) but I know the JB Weld stuff will.

It isn't exactly cheap ($200.00 investment that can be used numerous times?) but you can buy a plastic welder with plastic rod assortments from Graingers that uses hot air and weld it with a similar material rod. I have welded many types of plastic pipes from 3/4" up to 6" this way as a pipe fitter. It is actually stronger than PVC glue. Pipefitters handbook from Audel Publications (Barnes& Nobles) shows the exact procedure. Other option when all else fails and you do determine that you have to replace the joint is to use a black rubber (neoprene) transition sleeve from Home Depot plumbers section that uses hose clamps. Cut away both sides of leak and install. 15 minutes max time to do.

Best: Replace the section. Use proper pvc primer, then pvc glue. apply the glue to both male and female ends. Insert one into the other while twisting a quarter turn. This welds the pvc of one piece to the other (the twisting does the 'mixing' - at this point they will be permanently bonded, and impossible to pull apart. Let it cure for a few hours before getting water near it. Less good: If you attempt to reglue it - heat the section with a hair dryer for some time to ensure its totally totally dry. Let the section cool - the glue doesn't like high temperatures. Re-prep the 'purple' area with new abs primer and glue, and use a metal tool to smush the joints together - the plastic will be slightly liquified while the solvent is on it. Lesser good: If that doesnt work, dry it like in the previous suggestion, then apply silicone, and make sure it gets smushed into the joint really well with a wet finger. Other option: Theres a silicone self-sealing black repair tape that when you peel the backing off, it sticks to itself permanently. Tightly wrap the joint with this stuff. You'll find it at the hardware store in the plumbing section. Worst option - put a bucket under the sink. Empty it occasionally.

I have an official undying hatred for people that silicone leaking toilets in. That area under the toilet between the flange and the silicone is ....okay...until you take the toilet out. BLARGH. When I was hotel maintenance we had to replace a few - and one of the quick fixes instead of replacing the wax seal was just to silicone around the edge. Yuck...Years of sewage had been waiting for me until that day.

The main problem may be the design? If your picture is correct, you've got a larger size pvc on top with a female joint, attaching to a smaller pipe with a male joint, through the required reducer. When it comes to downhill flow, this is backward. It impedes the flow. Larger pipes shouldn't flow to smaller ones. In the direction of flow, whether it be gases or fluids, the male fittings should be closest to the source. But! If this is what you had existing, there was no other way to connect the larger, upper drain, to the smaller existing one? Since the epoxy will not flow uphill, into the joint, you're only option is to use caulk and try to force it up. Or build a collar or bead of caulk or putty just below the joint and then use a syringe or something to force the glue up into the joint. Make sure the joint is DRY. Don't use the drain for a day or two and let it dry out completely for any kind of success. Good luck!

Running this line of PVC took me all morning, and since I am loath to rip it all out and do it again, I covered the leaking area with bathroom caulk. If it holds for 6 months or more before I have to do anything, I'll consider it a win. By the way, I tried flowing more PVC primer followed by cement into the leak without success.

it cant be too hard to prepare a new middle section, apply new glue to top and bottom, and slide and twist both ends in at the same time... You'd have to be quick, but not too too quick. New flange, piece of pipe, and a joiner would only set you back a few bucks. Although - if the silicone holds out - all the power to you! These are tough times!

Turn off the water and dry the area where water is leaking out. Use some of the blue pvc cement made for plumbers. It's seals plastics/rubbers together well enough support over 200 psi. I had to use it plenty of times for my hydroponics setup for leaks. I use Rain-R-Shine PVC cement...just wear a mask, it's extremely volatile, but it's workable in 15 minutes, fully cured in 2 hours. Also, don't be afraid to use a wrench to get the can open...ours always seals itself closed.

If you can get the area dry enough, you may be able to use silicon or maybe better a hot glue gun and glue. There are other products that could due the job as well. Most times though, you are just putting a band aid, on the problem. A better fix would be to get a 2"x1 1/4" rubber no-hub repair coupling, it comes with steel clamps to tighten the ends. Cut the small leaking area out, don't worry about the gap, the fitting will handle it. Use a hacksaw to cut the pvc. The fitting should be less than $6 at Lowes or Home Depot. You with have to remove the clamps for now. It will be a bit of a fight, to get the coupler onto the hubs but it can be done. Dish soap might help. The clamps come apart to put around the ends of the hub. The clamp is usually a 5/16" nut with a slot for a screwdriver. Proper torque about 65 inch pounds, but just snug it up, run the drain and tighten some more if needed. I hope this helps.

to preface: I have several years of experience working in irrigation systems. If this is a non-pressure joint, I would expect any thing that adheres well to PVC would do well. Even re-gluing the join would probably serve the purpose. Allow for proper drying time for the glue.

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Bio:Eric J. Wilhelm is the founder of Instructables. He has a Ph.D. from MIT in Mechanical Engineering. Eric believes in making technology accessible through understanding, and strives to inspire others ...read more »